Numerical Feasibility Study of an Externally Heated Geothermal Bridge Deck

Geothermal energy is a renewable, sustainable, clean (i.e., zero carbon emission), and directly used an energy source that has been successfully used for bridge and pavement deicing. However, existing geothermal bridge/pavement deicing designs mostly rely on hydronic loops, which are embedded within concrete decks during bridge construction phase and are considered as internal heating. This paper presents a numerical feasibility study of an external geothermal heated bridge deck design in which the hydronic loops are attached to the bottom of the bridge deck and encapsulated in a layer of geofoam. A series of parametric analyses are performed to investigate the external heating process in comparisons to internal heating. These analyses contain various ambient temperatures, inlet temperatures, wind speeds, and flow velocities. The results demonstrate that external heating can heat the bridge deck to above freezing temperatures in mild winter weather compared to internal heating. Limitations of both heating systems are also evaluated since both systems would be unfeasible for extreme environmental conditions such as high wind speeds (more than 8.94 m/s) and lower ambient temperatures (lower than −2°C).